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Solar did not help meet peak demand today in California: http://www.caiso.com/Pages/TodaysOutlook.aspx http://www.caiso.com/Pages/TodaysOutlook.aspx Nor does so

Solar did not help meet peak demand today in California: http://www.caiso.com/Pages/TodaysOutlook.aspx http://www.caiso.com/Pages/TodaysOutlook.aspx Nor does solar help meet peak demand for 2/3rds of the year because peak demand comes after the sun goes down. Solar can help during some summer days, but for much of the year it makes the system less efficient by requiring more ramping up and down of other generation resources.

teach 10y ago
Once we get our Tesla Powerwall batteries, that should help with peak demand, no?
- Symmetry 10y ago
  Only if they sell power back onto the grid when there's more demand than can be met. Which is a doable thing but we don't have the framework quite in place yet.
  - philipkglass 10y ago
    Localized storage on households and businesses can help even if it never feeds back to the grid, because it means that batteries can charge via off-peak electricity and switch to discharging to fulfill local demand during grid peak times. It has pretty much the same system effect as discharging into the grid during peak demand but it's more efficient to use the electricity at the same point it was stored.
greglindahl 10y ago
Solar peaked at 8% of total production today, which looks like it matches the comment you're replying to: "At modest levels of penetration..."
philipkglass 10y ago
Even in summer in California solar peaks mid-day while demand peaks in early evening. Nevertheless, it appears that the additional costs and efficiency loss from cycling fossil plants is dwarfed by the fuel-consumption savings, at least up to modest (33%) penetration of solar/wind: https://www1.eere.energy.gov/wind/pdfs/55588.pdf https://www1.eere.energy.gov/wind/pdfs/55588.pdf In this study, we found that up to 33% of wind and solar energy penetration increases annual cycling costs by $35–$157 million in the West. From the perspective of the average fossil-fueled plant, 33% wind and solar penetration causes cycling costs to increase by $0.47–$1.28/MWh, compared to total fuel and variable operations and maintenance (VOM) costs of $27–$28/MWh. The impact of 33% wind and solar penetration on system operations is to increase cycling costs but also to displace annual fuel costs by approximately $7 billion. The modeling assumptions in that study look pretty reasonable to me. The one significant change I'd make is plugging in a lower natural gas price, e.g. the $3.66/MMBtu from Henry Hub a week ago, compared to $4.60 assumed in the study. Even with that change it looks like fuel savings dwarf cycling costs.
tedsanders 10y ago
This is such a frustrating misconception. The annual peak is far more important than the daily peak for capacity planning. There are two capacity issues being confounded here: (1) Generation capacity. The idea here is that if solar doesn't generate during peak loads, then building solar will not displace power plant capacity. But solar does generate during peak loads, so building solar does reduce the number of natural gas plants you need. At higher levels of PV penetration this will be a concern, but we're not there yet. (2) Ramping capacity. The idea here is that solar generation is correlated and non-dispatchable, so dispatchable generation must be able to match the swings in solar output. Again, this will be a concern at higher penetrations, but right now the grid can handle it. Philipkglass's replies are excellent.
ZeroGravitas 10y ago
You've already got a couple of good replies, but I just wanted to be clear about how far you've missed the point of what you're replying to. His point was that the absolute peak of the system is in the afternoon during the summer. Which is when solar is most effective, so it shaves this peak quite well. It's like profiling your application and finding the hotspot, that's the place you most want to fix. It'll not only generate some energy that's needed, it will save you building a whole extra plant that's only needed for a few hours a year, if it's distributed then it'll save you upgrading transmission for a peak that's only needed a few hours a year. You talk about today, which is in mid December, which in places that use air-con means the peak load today is about 1/3 or so of the peak in the summer. California has more than enough power plants to supply the load in the winter even if all solar was unplugged suddenly. That was the whole point of what you replied to.

teach 10y ago

Once we get our Tesla Powerwall batteries, that should help with peak demand, no?

Symmetry 10y ago
Only if they sell power back onto the grid when there's more demand than can be met. Which is a doable thing but we don't have the framework quite in place yet.
- philipkglass 10y ago
  Localized storage on households and businesses can help even if it never feeds back to the grid, because it means that batteries can charge via off-peak electricity and switch to discharging to fulfill local demand during grid peak times. It has pretty much the same system effect as discharging into the grid during peak demand but it's more efficient to use the electricity at the same point it was stored.

greglindahl 10y ago

Solar peaked at 8% of total production today, which looks like it matches the comment you're replying to: "At modest levels of penetration..."

philipkglass 10y ago

Even in summer in California solar peaks mid-day while demand peaks in early evening. Nevertheless, it appears that the additional costs and efficiency loss from cycling fossil plants is dwarfed by the fuel-consumption savings, at least up to modest (33%) penetration of solar/wind: https://www1.eere.energy.gov/wind/pdfs/55588.pdf https://www1.eere.energy.gov/wind/pdfs/55588.pdf In this study, we found that up to 33% of wind and solar energy penetration increases annual cycling costs by $35–$157 million in the West. From the perspective of the average fossil-fueled plant, 33% wind and solar penetration causes cycling costs to increase by $0.47–$1.28/MWh, compared to total fuel and variable operations and maintenance (VOM) costs of $27–$28/MWh. The impact of 33% wind and solar penetration on system operations is to increase cycling costs but also to displace annual fuel costs by approximately $7 billion. The modeling assumptions in that study look pretty reasonable to me. The one significant change I'd make is plugging in a lower natural gas price, e.g. the $3.66/MMBtu from Henry Hub a week ago, compared to $4.60 assumed in the study. Even with that change it looks like fuel savings dwarf cycling costs.

tedsanders 10y ago

This is such a frustrating misconception. The annual peak is far more important than the daily peak for capacity planning. There are two capacity issues being confounded here: (1) Generation capacity. The idea here is that if solar doesn't generate during peak loads, then building solar will not displace power plant capacity. But solar does generate during peak loads, so building solar does reduce the number of natural gas plants you need. At higher levels of PV penetration this will be a concern, but we're not there yet. (2) Ramping capacity. The idea here is that solar generation is correlated and non-dispatchable, so dispatchable generation must be able to match the swings in solar output. Again, this will be a concern at higher penetrations, but right now the grid can handle it. Philipkglass's replies are excellent.

ZeroGravitas 10y ago

You've already got a couple of good replies, but I just wanted to be clear about how far you've missed the point of what you're replying to. His point was that the absolute peak of the system is in the afternoon during the summer. Which is when solar is most effective, so it shaves this peak quite well. It's like profiling your application and finding the hotspot, that's the place you most want to fix. It'll not only generate some energy that's needed, it will save you building a whole extra plant that's only needed for a few hours a year, if it's distributed then it'll save you upgrading transmission for a peak that's only needed a few hours a year. You talk about today, which is in mid December, which in places that use air-con means the peak load today is about 1/3 or so of the peak in the summer. California has more than enough power plants to supply the load in the winter even if all solar was unplugged suddenly. That was the whole point of what you replied to.